The Behavior of Bolt Connections With and Without Preloading Subject to the Slip-resistance and Shear

A form of structural junction known as a bolted connection uses bolts to link two or more structural components of a steel structure. A type of threaded fastener known as a bolt has a male thread and a preformed, complementary female thread, similar to nuts. To build a bolted connection, it is crucial to understand the bolt value and joint strength concepts, which are further explored. When it comes to interchangeability—the ability to assemble and disassemble components mechanically and structurally—bolted connections enable more effective connecting of pieces. They are the most frequently utilized in the final assembly, already during construction, in a condition of final consolidation of the structure, and for this reason as well. This work began in a pedagogical action to compare the experimental results with those obtained by Eurocode 3 (EN 1993-1-8) in simple joints with screws subject to cutting, the study evolved to the analysis of the behavior of the screws themselves in the joint. Tests were carried out with great dimensional accuracy, for new bolted connections, with different bolt’s number, according to different arrangements and repeated in cases of simple and preloaded tightening. The experimental work, carried out on a uniaxial tensile testing machine, consisted in subjecting the connections to a growing effort so that the bolts, being subject to the cut, would break through the thread-free zone.The analysis of results and their comparison (in force - displacement diagrams) allow to draw conclusions regarding the true behavior of the bolted connections. The characterization of the thresholds of the initial zone of the force - displacement curves, in the cases of connections with preloading- was the objective of study. The transfer of forces and the influence of friction on the bonds without and with preloading were then characterized. The main objective of this project is to know the meaning of the calculated values in the preloaded and non- preloaded links by Eurocode 3.